Apple on March 18 sued Amazon.com for improperly using Apple's APP STORE trademark, according to a court filing.

The lawsuit was filed in a California federal court (Apple Inc v. Amazon.com Inc, 11-1327). Reuters reported that according to Apple, Amazon has improperly used Apple's APP STORE mark to solicit software developers throughout the United States.

Apple has also applied to register the APP STORE trademark in the United States, a bid which Microsoft opposes. Microsoft has filled a motion with US Patent and Trademark Office this week arguing that the generic term "App Store" should not be a trademark of a single company.

Apple had applied to have the term trademarked in 2008, shortly after it launched its App Store for the iPhone. Microsoft's motion points out that the term "app store" is used as a generic term by lots of companies to describe the online retail outlet used to sell mobile phone applications to consumers.

Microsoft added that companies Palm, Nokia, Research in Motion, Samsung and Google regularly use the "App Store" description. Last January, Microsoft filled a motion with US Patent and Trademark Office arguing that the generic term "App Store" should not be a trademark of a single company. Microsoft's motion pointed out that the term "app store" is used as a generic term by lots of companies to describe the online retail outlet used to sell mobile phone applications to consumers.

Apple had applied to have the term trademarked in 2008, shortly after it launched its App Store for the iPhone.